Buffy-Tufted-Ear Marmoset, Callithrix aurita
BUFFY-TUFTED-EAR MARMOSET
Callithrix aurita
Geographic Distribution and Habitat
The buffy-tufted-ear marmoset (Callithrix aurita), also known as the white-eared marmoset, is endemic to south-eastern Brazil—specifically in the montane rain forests (high-altitude rainforests along mountains and plateaus with high levels of rainfall) of Rio de Janeiro, southern Minas Gerais, and north-eastern São Paulo.
Though there have been many discrepancies and unconfirmed information regarding the range of this species, their geographical boundaries are generally as follows: In Minas Gerais, the species has been recorded living north of the Rio Muriaé in Rio Doce State Park, as well as hybrids between them and the buffy-headed marmoset occurring at Carangola in the Serra do Brigadeiro. Their northern limit appears to be Minas Gerais’s Rio Piracicaba, with Rio Doce being their southernmost boundary in the state. In East Rio de Janeiro, the buffy-tufted-ear marmoset is confined to the tops of the slopes of the Serra do Mar, though they can be found nearly at sea level in the southern part of the state. Their southernmost occurrence is that of São Paulo, and while specifics are confirmed, it is generally believed that they reside only north of the junction of the Rios Pinheiros and Rio Tietê.
At the end of the 20th century, it was argued that the buffy-tufted-ear marmoset and the buffy-headed marmoset might be subspecies of the common marmoset, due to their similar behaviors, dental structure, fur (especially as infants, when the two are nearly identical), vocalizations, and the fact that wild hybrids of the two were found in Carangola, Minas Gerais. This concept was further studied in 1996, and it was determined that the kindred buffy-tufted-ear marmoset and buffy-headed marmoset were actually two separate, full species; their vast array of similarities was credited largely to the adaptable nature of marmosets.
Size, Weight, and Lifespan
On the smaller side for primates, these marmosets typically weigh between .6 to .8 pounds (10 to 13 ounces), though some have been observed weighing up to a full pound (16 ounces)! They have a body length of around 7.5 – 8.5 inches (19 – 21 centimeters), with long tails that can span up to 14 inches (35 cm). No major differences in size are noted between the males and the females of the species.
The buffy-tufted-ear marmoset has a rather short life span, typically living between 7 to 16 years in captivity, and only an average of 12 years in the wild.
Appearance
These guys definitely call for a second glance, with their unique color patterns and human-like faces that almost seem to be sporting black clown makeup over their eyes. As suggested by their name, a defining quality is the short tufts of hair that stick out from their ears into little points, often white but sometimes ranging to a tan, brown, or gray. They most commonly have black fur covering their bodies, though sometimes observed with orange or brown spots or markings sprinkled in. The tops of their heads usually are coated with a thin cap of tan or orange, giving them the appearance of a receding hairline. Their long tails are non-prehensile and lined with black rings.
Their faces are white to light tan and furry, usually with black, diamond-like “eyeshadow” that surrounds their amber eyes. They have short snouts and flat noses, with downturned mouths.
Diet
Classic omnivores, the diet of the buffy-tufted-ear marmoset consists of a wide range of different kinds of food. A study published in 2000, monitoring the daily feeding activities of this species in forest fragments of southern Minas Gerais from October 1994 to September 1995, found that just over 50% of their diet consisted of tree gums. 82% of this gum intake came from the Acacia paniculata, which they fed on year-round. Other food sources included fruits (varying types from season to season), flowers, insects (like caterpillars, katydids, homopterans, ants, and cockroaches), eggs and larvae, and small animals like lizards and frogs. Their intake of animal matter increases during the dry season when plant-based fuels are less abundant.
Most marmosets possess a type of incisors that allows them to better harvest gum from tree branches and trunks—the buffy-tufted-ear marmosets do not. To get this precious food source, they have to find places where it is easily available without needing to be gouged out, often relying on previously gouged trees and returning to the same site time and time again.
Behavior and Lifestyle
This species is diurnal, meaning they are active during the daytime, and arboreal, spending the majority of their lives in the trees. Feeding time typically takes place within the first 30 minutes of their day, when they wake up after sunrise. They will feed heavily for around an hour, then use all that energy to…well…just enjoy the rest of their day by resting, socializing, and snacking when they spot more food. When they eat, they use their hands to pick up and hold their food. They are typically less active during hot dry periods.
These monkeys are quite understudied, so there is still much to be learned about their behavior. It is likely that the buffy-tufted-ear marmoset can skillfully navigate the canopy layer quadrupedally and hang vertically from a branch using their sharp nails to latch onto the bark, like the closely related buffy-headed marmoset.
When the sun is about to set, these marmosets gather at their sleeping site, nestling among the vines and branches in groups for safety in numbers and camouflage from predators.
The buffy-tufted-ear marmoset is one of the only primate species that eat bamboo fungi! This is most likely a testament to the adaptable nature of this monkey, as it’s mostly recorded in areas where fungi are abundant. This dietary choice is only otherwise observed in buffy-headed marmosets and Goeldi’s monkeys.
Group sizes for this species range from 4 to 15 individuals, with ranging gender ratios. There is typically only one breeding female within the group during the breeding season, even if there are multiple sexually mature females within the group. This is likely because the entire group participates in the nurturing of an infant. A female who breeds often within a group likely plays a dominant role within the hierarchy, along with her partner.
Home range sizes can be around 40 hectares (.15 square miles), as was observed for one familial group living at the Bananal Ecological Station in São Paulo.
There is still much to be discovered about the group dynamics and daily life of a buffy-tufted-ear marmoset, though some general information can be gathered from observing that of the common marmoset. Unlike most primates, who leave their birth groups during adolescence, common marmosets wait until adulthood to move out. If a family unit has two breeding females, one is usually dominant, while the other, often her daughter, takes a subordinate role. Other social hierarchies are often determined by age.
Marmosets are highly communicative in general, utilizing many different forms to convey specific messages. They possess a range of vocal calls that they sometimes pair with certain postures. Their alarm calls, a repeated staccato sound much like a “tsik,” can be heard from far distances and are used to warn group members of potential threats, that they usually accompany with a partial, open-mouth stare. Other postural messages include a frown to convey anger or aggression, narrowed eyes to show submission, and lowered ear tufts to indicate fear or curiosity. Another vocal call — trill calls — are lower pitched and used to keep tabs on other group members. “Phee” calls, the highest pitch of the three, are more like whistles and can be used for a larger range of messages including defense and mating calls.
Females can use a chemical cue that suppresses the hormones of other females, to instate dominance and ensure that they are the only female to breed in a group. Other chemical-based communications are olfactory, related to smell. Utilizing scent glands on their chests and near their genital regions, marmosets can spread secretions on tree branches to illustrate their reproductive status. Other marmosets then use a specialized organ in their nose to understand what these secretions convey.
Lastly, like many primates, grooming is a major form of social bonding for marmosets and is often utilized by lower-ranked members to help facilitate positive relationships with dominant members.
There is typically only one breeding female within each familial group, who heads the troop alongside a male partner. This female will release a chemical cue that aids in suppressing the hormones of those lower-ranked females in the group. Monogamy is common (with groups generally relying on the same breeding pair at a time), and genetic diversity is maintained by abstaining from inbreeding with other family members. Gestation (pregnancy) lasts around 170 days, after which it is most common for fraternal twins to be born (though sometimes there is only one young birthed). Though there is only one birth mother, the entire group assumes care duties of the infant, which increases its chances of survival. The mother typically handles transportation, with the infant/s grasping onto her chest while the group travels. As the infant grows, it will graduate to holding onto their mother or father’s back. The young are weaned at 3 months old, and reach sexual maturity at around 1.5 years for females and just over one year for males. Once they have reached adulthood, they usually will leave their familial unit to go find another group and form new pairs. Departure from the troop prevents inbreeding. It is more common for males to leave than females.
Though not much research has been done regarding the ecological role of the buffy-tufted-ear marmoset specifically, much can be assumed based on the information we do know. For starters, their fruit-heavy diet helps disperse seeds through their droppings. Their feces also serve as fertilizer to the soil and can facilitate seed germination. They also contribute to foliage health by pruning leaves from the trees as they forage for plant gums, as well as limiting insect populations that can threaten plant life.
The buffy-tufted-ear marmoset is classified as Endangered by the International Union for Conservation of Nature (IUCN, 2015), appearing on the IUCN Red List of Threatened Species. Their population size has reduced by over 50% over the three generations (2000-2018) due to a number of threats including hybridization, live capture for pet trade, and, primarily, habitat loss. It is suspected that over 40% of their natural habitat has been destroyed, and this number is growing. The valley of the Rio Paraiba and the lowland forests have been especially fragmented, as a result of human activities. The species is already considered extinct in lowland forests of São Paulo.
With already dwindling resources, the buffy-tufted-ear marmoset also has to manage competition from other invasive marmosets, like the introduced common marmoset and black tufted-ear marmosets. On top of added competition for resources, other marmosets put the buffy-tufted-ear marmoset at risk of extinction by hybridization, the interbreeding of these differing species. Over time, this could potentially eliminate what is left of the genetically pure individuals in the wild.
A yellow fever outbreak from 2016 to 2017 also imperiled the species, with over 250 confirmed cases of infection (though the actual number is probably much higher)
Buffy-tufted-ear marmosets are listed in Appendix I of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival. There are also a large number of protected areas where these animals can safely reside, including but not limited to:
- Over 12 zones in Rio de Janeiro, totaling over 240,000 hectares (930 square miles)
- 6 zones in Minas Gerais, including Rio Doce State Park and Serra do Brigadeiro State Park
- Over 25 zones in São Paulo, totaling over 1,300,000 hectares (5020 square miles)
Researchers with the Environmental Research Institute of Sao Paulo partnered with Sylvamo, a global paper company who are “committed to sourcing 100% of [their] fiber from sustainably managed forests, while safeguarding forests, biodiversity, and watersheds,” to keep track of high biodiverse species on one of the company’s reserves: Reserva Particular do Patrimonio Natural.
Another partnership, between the Brazilian Institute for the Environment and a local non-governmental organization called “Pr6-Bocaina,” was formed with the goal of creating general conservation awareness and tackling the issue of untrained forest guards in certain reserves/parks.
The Mountain Marmosets Conservation Program (MMCP), established in 2014 to tackle rising threats to the buffy-tufted-ear marmoset, set out to identify regions with pure populations, hybrid groups, and invasive species. They located 85 groups of pure buffy-tufted-ear marmosets and 47 groups of invasive species or hybrids in around 100 different areas. This new information highlighted the urgency and impending danger that hybridization and invasive species, in general, were causing. A plan was created in 2017 that aimed to boost population numbers and support any identified strong reproductive pairs, though MMCP is still urging more institutions to join in order to increase the effectiveness of their plan.
Other organizations that have put forth conservation plans include The National Action Plan for the Atlantic Forest Primates, the Maned Sloth, and the Rodrigo Salles de Carvalho of Rio de Janeiro University.
The IUCN has recommended a series of further required conservation actions, including improvement of land/water management and site/area management. They also listed how critical it is that more research is done on this species, especially regarding population size, distribution and trends, life history & ecology, and threats. These marmosets must continue being monitored with population trends closely followed, and much work is still needed to ensure the survival of this beautiful and unique creature!
- https://www.iucnredlist.org/species/3570/191700629
- Coimbra-Filho, A. F., Pissinatti, A. and Rylands, A. B. 1993. Experimental multiple hybridism among Callithrix species from eastern Brazil. In: A. B. Rylands (ed.), Marmosets and Tamarins: Systematics, Ecology, and Behaviour, pp. 95-120. Oxford University Press, Oxford, UK.
- Ferrari, S. F., Corrêa, M. K. M. and Coutinho, P. E. G. 1996. Ecology of the southern marmosets (Callithrix aurita and Callithrix flaviceps) – How different, how similar? In: M. A. Norconk, A. L. Rosenberger and P. A. Garber (eds), Adaptive Radiations of Neotropical Primates, pp. 157-171. Plenum Press, New York, USA.
- Melo, F.R. and Rylands, A.B. 2008. Callithrix aurita (Geoffroy in Humboldt, 1812). Pp. 735-737. In: Machado, A.B.M.; Drummond, G.M. & Paglia, A.P. (ed.), Livro Vermelho da Fauna Brasileira Ameaçada de Extinção, pp. 907. Ministério do Meio Ambiente e Fundação Biodiversitas.
- Olmos, F. and Martuscelli, P. 1995. Habitat and distribution of buffy tufted-ear marmoset Callithrix aurita in São Paulo State, Brazil, with notes on its natural history. Neotropical Primates 3(3): 75-79.
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Written by Hannah Broadland, March 2025